The overall objective of this research is to isolate and identify metabolites and oxidation products of vitamin A and related retinoids. Metabolites will be isolated from numerous tissues of chicks or rats which have been maintained on either retinol, retinoic acid or related compounds as their only source of vitamin A. Metabolites will be purified by high-performance liquid chromatography and identified by nuclear magnetic resonance, infrared, ultraviolet and mass spectral analyses. The biological activity of isomers and metabolites of retinoic acid will be assayed in rats and/or chicks.